Solid state drives (SSDs) often use multiple NAND flash memory blocks or modules to increase storage capacity. However, each NAND flash memory module has a limited number of write or erase cycles before it breaks down and this can affect the reliability of the SSD, especially in an environment where the host accesses of the SSD are unpredictable. Without any control of the write or erase operations to a particular SSD, some NAND flash memory modules may be written or erased more frequently than the other modules and therefore affect the reliability or life-time of the particular SSD.